If you’ve ever run a marathon, thought about running a marathon or watched someone you love run one, you understand the pain. You see those faces and those strides mere yards from the finish line. You see happiness and even tears struggling past unrelenting physical torment. You sense the adrenalin that is coursing, grasp that the last possible bits of energy are being summoned. Joy is rising and overtaking pain. The finish line is the joy line. The finish is the ecstasy after the agony.

Now imagine that high that marathon runners embrace and even crave being jolted from mind and body by an eruption nearby, of tremors, shock, debris and then a second similar blast, and you hear screams and see runners around you falling, see blood on the pavement and other unimaginable sights. You smell smoke and sense death. That finish line and ultimate joy are gone in a tsunami of pain, fear and even shock.

A marathon runner by nature is a person at war with his or her body to complete an hours-long process of abuse, of survival. In downtown Boston on Monday afternoon, those definitions changed forever. Pain and survival now will be measured by walking away in one piece and finding family and friends whole from the splintering assault of a terrorist’s exercise in cowardice.

This may feel a bit remote to you. You may never have known anyone who ran a marathon. You watch what has happened in Boston the same way you have watched other terrorists’ attacks. You are angered appropriately, but maybe you are not seeing how this is different.

You might find it impossible to comprehend how hard it is to push yourself one step at a time from, say, KY 55 to downtown Louisville. You don’t taste that finish-line euphoria and relief and can’t quite grasp how that feeling was stolen from so many thousands on a clear and beautiful Patriot’s Day.

Full disclosure: I’ve never run a marathon, either, although I’ve done half of one. I’ve been a fairly consistent if non-competitive runner for more than 30 years. I get a part of that marathoner’s experience.

But my greater understanding comes from watching the unadulterated courage of my wife as she step-by-step has completed two marathons in difficult conditions. I saw what she put into those races, how she pushed and clawed and trotted and panted and puked in heat and wind and pain. Then I saw her at the finish line and the exquisite pureness of her joy. I hugged her sweaty euphoria and tasted the tears of that joy. I get all of that.

Perhaps that’s why Monday’s awful explosions at the end of the Boston Marathon moved my personal Richter Scale at a shivering intensity. This angers me far more than most such attacks, maybe anything short of Sept. 11 and Newtown. This one I take personally because I see a devastating assault robbing the innocent of overwhelming accomplishment.

This crime stole lives, stole limbs, stole personal peace, stole a personal event of great importance to a great city, stole from Americans a great tradition.

The Boston Marathon has been a curiosity for me ever since as a cub reporter I sat down for pancakes with a woman named Gayle Barron, a TV reporter and local-star road racer who in 1978 stunningly had won the women’s half of that race. She told me what that accomplishment meant to her and explained the example it would set for others. She sketched a mission and described success that I would encourage others to pursue.

And such pursuits are why I understand a marathon of this magnitude would be an easy target for devious, with its passive, milling, backpack-laden herds of fans and competitors, its plodding processional with simple congregation points stretched over several zip codes, with thousands upon thousands of the most innocent poised to cheer that big finish, creating a maniac’s gunnery range, it would seem. The carnage could have been so much worse.

Some years ago my wife and I decided to run in the Peachtree Road Race, a 10-kilometer jog from the Buckhead area of Atlanta right through the city to Piedmont Park. It’s a hilly and lovely course, and on the morning of July 4th more than 50,000 annually line up in holding pens like cattle awaiting slaughter.

In groups of thousands we were walked to the start line and were sent off in waves, meaning that by the time the winners passed the finish line, perhaps all 50,000 were in slow motion down Peachtree Street. Can you envision that en masse opportunity? If you were one of them, like I was, and now have seen the videos and heard the testimonies from Boston, you shudder a bit. You chillingly envision a milieu for madness.

But nothing truly stuns me anymore. If mad Americans can assemble bombs from fertilizer and blow up federal office buildings or buy high-powered weapons and open fire on children or moviegoers, I don’t focus all of my rancor on those misguided murderers from the Middle East, either.

I just know that with the hundreds of lives disrupted if not destroyed on a peaceful Monday, this time the bad guys hit lower and harder below the belt of human endeavor.

Those were marathon runners out there setting an exemplary pace for all of us, and their finish line was redrawn for the rest of their lives by orchestrated mayhem.

If you know a runner who endures that pain, hug him or her today. All runners have lost an even bigger race.